CHENNAI (Metro Rail News): CMRL has ventured into extensive infrastructure development in the city comprising three more metro rail corridors for a total length of 118.9 km & 128 no’s of stations being funded by several multi-national funding agencies, including the JICA, ADB and AIIB.
The first TBM tunnel drive in Phase II has already commenced, and CMRL has undertaken several safety measures in TBM tunnelling to ensure the public’s safety. Thiru. T. Archunan, Director(Projects), has said, “Several safety measures are being undertaken during the tunnel drive as there are various parameters to be monitored while the TBM is being operated like water pressure adjustment considering the water table in the area, even the slightest modification will impact the roads on the Surface and nearby buildings. Hence its most crucial that we monitor every 50m to ensure smooth and safe working space in the area without creating impact.”
Safety Preventive measures in TBM Tunnelling
Ground Monitoring instruments are installed in-ground Surface above the tunnel alignment.
Structural monitoring instruments are installed in the buildings above the tunnel influence zone.
The instrument readings are recorded daily during TBM Tunnelling.
The Surface monitoring team ensures ground distortion observation during tunnelling.
Existing building surveys, including Structural & Plastering cracks, are recorded and acknowledged by residents.
The building cracks that are found widen after the TBM crossing are entirely repaired.
All bore wells/Open wells in the influence zone properties are considered for Temporary/Permanent plugging.
Permanently plugged bore wells are provided with alternate bore wells.
Open wells must be closed and provided with alternate bore wells.
Bore wells which are plugged temporarily during TBM pass-through, adequate water supply is ensured for the residents.
In case buildings are listed as unsafe, evacuation of occupants is ensured with alternate accommodation for two months or as required.
In the event of any old-age building being structurally unsafe after tunnelling, new
construction will be considered.